变压器油结构组成对其氧化安定性与析气性的影响

Effect of transformer oil structure composition on its oxidation stability and gassing property

以中海油环烷基常二线馏分油为原料,LH-23和RJW-2为加氢催化剂,采用不同加氢工艺制备变压器油基础油,分析了基础油结构组成对其氧化安定性与析气性的影响。结果表明:随着变压器油加氢反应温度升高,精制程度加深,基础油中饱和烃(总链烷烃和总环烷烃)的质量分数由64.2%增至80.6%,芳烃的质量分数由35.8%降至19.4%,氧化后的酸值逐渐降低,基础油的氧化安定性变好,但同时析气值逐渐增大,析气性变差;同时,基础油中多环芳烃质量分数由1.7%降至0,双环芳烃质量分数由12.0%降至2.6%,单环芳烃质量分数由22.1%降至16.8%,多环芳烃较单、双环芳烃对基础油氧化安定性的影响更大;在芳烃总碳原子质量分数(CA值)为8.5%的基础油中加入萘的质量分数仅为1%时,油品的析气值由5.3 mm^3/min降至-3.5 mm^3/min,双环芳烃更适合改善基础油的析气性;为使变压器油基础油兼具良好的氧化安定性与析气性,基础油的C_A值应保持在9%~13%。

The transformer base oil was prepared by different hydrogenation processes using CNOOC naphthenic second-line distillate, LH-23 and RJW-2 as hydrogenation catalysts. Then the influence of base oil structure on oxidation stability and gassing property was analyzed. The results showed that when hydrogenation temperature increased, the refining degree had deepened, the fraction of saturated hydrocarbon(paraffins and naphthene) in the base oil had increased from 64.2% to 80.6%, and the fraction of aromatics had decreased from 35.8% to 19.4%.The acid value after oxidation decreased gradually, and the oxidation stability became better, but the gas evolution value increased gradually, and the gassing property became worse. At the same time, the fraction of polycyclic aromatic hydrocarbons(PAHs) in base oil decreased from 1.7% to 0, the fraction of bicyclic aromatics decreased from 12.0% to 2.6%, the fraction of monocyclic aromatics decreased from 22.1% to 16.8%, the influence of PAHs on the oxidation stability was greater than 1-2 ring aromatics. When the fraction of naphthalene in base oil of which the CA value was of 8.5% was only 1%, the gas evolution value decreased from 5.3 mm^3/min to -3.5 mm^3/min, which showed bicyclic aromatics was suitable to improve gassing property of the base oil. In order to make the transformer base oil had good oxidation stability and gassing property, the C_A value of the base oil should be kept at 9%-13%.